Screw jack



J. F. PARKER SCREW JAbK Filed larch 12, 1925 Patented Oct. 6, 1925.

UNITED -QFN BARKER. Q 3931 14332 ssae est- ,e pli ti'qn e wrehl S rial.N 51

. T0 all'whom it may concern:

The principalobject of my invention, is

to produce a simple, efiicient device, not easily disabled or liable tofail when most needed. and on which. may be used to espea a crcumferential shoulder 6 which bears'on. the top of the base andsupports the column.

ci-al advantage in motor vehicle work, yet adaptable to any liftingoperation within its capacity.

Another object is. to, procure. a so-called knock-down feature, whichenables the user to pack it in a comparatively small space fortransportation.

And still another feature which very largely increases itsusefulness isthe provision made for increasing its height when rcqnired, thus makingit available for use 1n either low or high hung vehicle runn ng gears.

Other objects will be apparent from read} ing the description containedin my SIJGClfi:

cation when taken in connection with the.

annexed drawing, which discloses one embodiment of my invent on and 1HWlllCh like characters of'reference refer to similar parts;

throughout all the different views,

In the drawing Fig, 1 is an elevation, mostly in section,

ofmy jack;

Fig. 2 is aplan view of the base;

Fig. 3 is a plan view of the nut;

Fig. it is a side View of the nut;

Fig. 5 is a fragmentary section of a part ofthe base, taken on line 55,Fig. 2

Fig. 6 is a plan view of the lifting head;

Fig. 7 is a section through the column and screw, taken on line 77, Fig.1;

Fig. 8 is a section. through the same parts, taken on line 88, Fig. 1;'

Fig. 9 is a side elevation of the lifting head. and. raising block Fig.10 is a section through the above parts, taken on line 10-10, Fig. 9,and

Fig. 11 is a view, in perspective, of the lower portion of the column.

Referring to the drawings, 1 is the base of the jack, preferably maderound at the bottom a d rising in a conical iQ Z Q 9 he 19- An opening2, on the upper end, receives'the.

column 3 and'is soimade that a locking 'f'ea ture is obtained. Byobserving 2 it will be seen that this opening is a combination. of twoconcentric circles of different diameters, the rg of th wo be n Qf sucha size as to easily allow the ears 5, of the column t0 pa s the ethougha aft which by a quarter turnof the column these ears may slip underthe overhanging shelves or flanges 5 forming the smalle fof the two.

circles, "and prevent a withdrawal of the column from the base.

Placed above the ears 4, on the column,-is

and any weight put thereon in operating the jack. To more fully lock thecolumn to. the base,,and prevent its turning thereon, I provide on thecolumn the earsl7, and pivotally mount'betweenthem the pawl 8 which maylodge, when in locked position, in the recess.

9 formed in the side of the base, near the top. The column is thereforeheld against.

rotation on. the base by the pawl 8, and against withdrawal from thesameby the ears 4:. i 011 h t f the 01 11 11 i a lange outwardly disposed,andturning on which is a, member 11',, havinga two-fold function.

. on the larger of the two shoulders 17,.isa

collar 18, having ears 19 extending upwardly and between which ispivoted, on the pin 20, the pawl 21. To hold the collar (18) inposition, vertically, a second collar, 22, fitting the smaller of thetwo shoulders 23,. is fixed on the member 11 by the screws 21-.

n the e re 'upper end o the screw nd'fiXd t rned .dTQ pcrticn, thereof,is the lifting head 25'. 'As will'be seen in Figs. 1 and 10 the topsurface of this head is slightly concave, but at one side it rises, asat 25, to a considerable distance above the central portion. This servesas a lateral stop for the jack as it is slid under the axle housing, orother jack contacting point, of the vehicle. i

An extended portion, 27, of the pawl 21, has a tapped hole 28 thereinwhich provides means for inserting a handle 29 with which to actuate thenut.

To key the screw 14: to the column 3 and thus prevent it from rotatingwith the nut 13, when the latter is rotated in the process of operatingthe jack, I cut, or core, keyways 30, extending from the bottom of thecolumn to the flange on the top of the same. These key-ways engage eachend of a pin, 31, extending through the screw 14 at a spaced distancefrom the bottom end thereof.

The height of my jack, using the plain lifting head, is admirablyadapted for use under the lower hung vehicles. It is often necessary tooperate it under those having their running gear a considerably greaterdistance from the ground. To meet this contingency I provide at raisingblock 32 which may be a temporarily fixed part of the lifting head, oras I preferably construct it, a quick detachable element. The bottom ofthe block closely fits the top surface of the lifting head and to moresurely hold it in place, while in use on the head, I provide dependingwings 33, filling depressions 34; made in the sides of the lifting head25.

In operation, the jack is placed under any part of the vehicle underwhich it is proper to lift,the screw having previously been raised sothat the lifting head lightly contacts with the lifting point. Assumingthat the: screw is cut with a right hand pitch thread, as shown,(although either right or left hand threads .may be employed) then amovement of the hand lever 29 to the left will start the screw upwardly.After making a convenient movement to the left, the lever is lifted (seedot and dash lines, Fig. 1) an amount-sufficient for the pawl 21 toclear the teeth 12 and a reverse movement to the right is made. Thelever is then dropped,allowing the pawl to seat in one of the toothspaces and the operation of oscillating the lever backwardly andforwardly is continued until the proper and desired lift has been made.I

In heavy lifting it would be advantageous to construct the screw using asingle pitch thread. 011 lighter work, and where time is a more valuableconsideration than power, 1 may elect to make this thread either doubleor triple.

To reduce the lifting movement of the hand lever when reversing, I bevelthe tops of the teeth 12,tapering them toward the top.

It will be observed, by examining Figs. 2 and 8, that the column 3 maybe inserted in the base in two ways. The locking parts being double, ortwo in number, and symmetrical, the column may be inserted in the base,then taken out and turned 180 degrees and reinserted. In either case itis entered, turned to the right until it brings up on the stop 35located beneath and at the end of the overhanging flanges 5, and thelocking pawl 8 dropped into place.

In the description and illustrations of my device I have presented oneembodiment of my invention. I shall feel at liberty to depart from theexact mechanical construction as herein set forth, in cases where I deemit expedient, provided, however, that all such changes shall not be inconflict with the meaning and intent of the invention and shall fallwithin the scope of the appended claim.

What I claim is:

In a screw jack, the combination, with a tubular body member having anut rotatably mounted thereon and a screw adapted to engage said nut andto operate within and above said body member, and with means to actuatesaid nut, of a base member having an aperture in the top thereof throughwhich the lower portion of said body member may pass, a circumferentialflange on said body member adapted to bear on the top of said basemember, a flange on the top of said base member projecting inwardly andwith portions in opposition cut away for a spaced distance, lugs on saidbody member beneath and separated a spaced distance from saidcircumferential flange and adapted to enter the spaces where said basemember flange is cut away, and positioned, vertically, so as to engagethe under sides of said base flange when said body member is oscillateda pre determined distance on said base member, whereby the said basemember flange may serve as the tongue and the space: between the lugsand the circumferential flange of the body member may serve as thegroove, and together, constituting vertical locking means for the twomembers, stops on said base member against which said lugs may abut,restricting the lateral movement of said body member, a pawl pivotallymounted on said body member and adapted to engage a depression on thesaid base member and constituting lateral locking means for said bodymember on said base member, sul stantially as described.

JOHN F. PARKER,

